Mechanical rectifier and means for improving the operation of the same



u! 3. JENNINGS.

MECHANICAL HECHFIER AM} mares FOR IMPRUVSNG THE UPERAUON OF THE SAME.

MPLICAIEUN FILi) MAR. 2 IQIIA 1,336,564. Patented Apr. 13, 1920.

Fig 0 F29, Z 5 I i WITNESSES: I INVENTOR da 412W UNITED STATES PATENTOFFICE.

HOUSE ELECTRIC AND MANUFACTURING COMPANY,

SYLVANIA.

A CORPORATION 0. PENN- MECHANICAL RECTIFIER AND MEANS FOR IMPROVING THEOPERATION OF THE SAME.

Application filed March 2. 1917.

To alJ "Ilium, it may concern, I

Be it known that I. OLIVER S. .lnnNns'us,

a. citizen of the United States. and a resident of lVilkinshurg, in thecounty of Allegheny and State of Pennsylvania. have invented a new anduseful Improvement in Mechanical Rectifiers and Meansfor lmprovin; theOperation of the same. of which the Following is a specification.

My invention relates to mechanical recti tiers of the commutator type.and it has for its object to provide a mechanical rectifier that shallbe both self-starting and selfsyin-hrimizinn.

Another ohjcct of my invention is to provide means for so altering theform and characteristics of the pulsating current wave produced hy therectifier as to reduce the percentage of periodic variation occurrin;therein.

Mechanical rectitiers ot' the conunutator type, as heretoforeconstructed. have usually comprised a cimunutator cylinder operalivelyconnectwl to a driving motor that rotates the commutator cylindersubstantially in synchronism with the frequency of thealternating-cnrl'eni supply. ll'ith such a device, ditiiculties havearisen in starting and in maintaining; the commutator cylinder atsynchronous speed.

According to my ix'n'ention. I provide a mechanical rectifier comprisinga rotatable armature n emher ]')rovided with a commutator cylinder andwindings so connected thereto that the device is not only selfstartiin,hut is adapted to operate. continuously at substantially synchronousspeed.

lt is well known that rect fying devices of the ahovc-dcscrihed typeproduce a rntl r peaked rectified current are having' a. r: a livelyhigh percentage of periodic voila tion. I propose to cut down thepulsations in the rectified wave and to prevent the ocurrenceol' zerovoltage by connecting a. corrective device in the receiving: circuit.

in the accinnpanying' drawings, Figilre 3. in a. diagranunatic view ofthe arrangement a 1.. circuit connections of a rectifier constructed inaccordance with my inventionz Figs. 2 and 3 are diagrammatic viewsrespectively showing the circuit connections Specification of LettersPatent.

Patented Apr. 13. 1920.

Serial No. 151.979

of corrective devices that are employed to improve. the wave forms ofapparatus embodying my invention. and Fig. l is a diagrammatic showingof the waveforms ohtained under various conditions.

The rectifier comprises a stationary field magnet 1, and a rotatahlymounted armature 2 which comprises a commutator cylinder 3 and aniagnetizahlc core member 4. The armature core member 4- is providedwith radial proiections 5 that are spaced approximately (50 apart. Threeconducting segments 6 of the commutator cylinder 3 that are spaced 12apart are connected to a slip ring 7 and three other segments 8 that areintermediate the hars (i are also spaced 121) apart and are connectedtogether hy a ring: 5!. The projections 5 of the armature core 4 areprovided with exciting coils [U which are connected in series relationhetween the collector ring 7 and the connecting rin; S) and are arrangedto produce alternate poles upon the core memher 1'. 'lhe projections 5are further provided with auxiliary coils 11 which are closed uponthemselves and are preferably of large cross-sectional area. as comparedwith the exciting coils 1.0.

Diametrically disposed hrushes 12* and I2" coact with tile commutatorcylinder 3 and are connected to the terminals of the secondary winding13 of a supply transformer 14, the primary winding 15 of which isconnected [on suitahle source of alternat ingr current, such, as asingle-phase generator 16. The pole pieces 1 are provided withfield-magnet windings 17 that are connected across the secondary winding13 and are arranged to produce opposite poles. .A brush 18 coactswviththe collector ring 7 and is connected to one main 19 of a receivingcircuit, the other main 2G of which is connected to the middle point 21of the secondary winding 13. A transformer 22 is connected in t ereceiving circuit, with its primary Wincmg ZR in series-circuit relationwith a. resistance load 24, which may he a storage hattery or some othertranslatingdevice. The secondary winding 25 of the transformer 22 isconnected between the mains 19 and 20, so that the induced voltagecreased by the effect of t e coils 11 and there will be no load upon thearmature, its

' member 4.

speed will increase rapidly. As the speed of the armature 2 approachessynchronism. the current flowin through the coils '10 tends to become umirectional and to establish substantially fixed poles on the core Atsynchronous speed, fixed poles are established on the core member andthe machine will then operate and develop considerable torque as asynchronous motor. It the s eed of the armature tends to exceed or falbelow synchronism under a varying load, the damping etl'ect of theshort-circuited coils 11 will oppose this hunting-action and tend tomaintain the armature insynchronism. At synchronous speed, analternating-current wave of one polarit will flow during one-half of acycle from t e brush 12to the slip ring 7. The.

current divides at the-slipring' 7. a portion traversing thedirect-current mains 19 and 20 and the load 24 and from thence hack tothe neutral point 21 of the 'windingJil and the remaining portiontraversingx-the exciting windings 10, the connecting ring 9 and thebrush 12" and from thence back to the other terminal of the winding 13.As;

the polar projections 53 are spaced (10 apart. it will be readilyunderstood that thc armature Wllllillll'l through 60.during cach halfcycle. Consequently, an alternating-current wave of the op ositepolarity will flow during the other ha f cycle from the brush 12 to theslip ring 7 from whence it divides. as described above. so that the flowof current through the direct-current mains 19 and 20.nnd through theexciting coils 10 is always-in the same direction.

From the foregoing, it is apparent that a mechanical rectifierconstructed in accord ance with my invention will start and come intosynchronism with the frequency of thc alternating current supply withoutthe aid of an auxiliary starting devices and that it wi continue tooperate at substantially synchronous speed.

Leferring to Fig. 4, the wave form of the alternating-current supplyvoltage is shown at A and the wave form of the rectified-current isshown at B. With the transformer 22 connected as shown in Fig. i! andwith an oseillograph 0 connected directly across the terminals of thesecondary winding 25, the wave foi m ot' the induced volt;

age, as determined from the oscillograph ue will be in-' 0, is shown atC, it being noted that this wave has double frequency of the wave A.With the oscillo a h 0 connected as shown in Fig. 3, the ha l wave-formof the rectified current passing through the directcurrent, load 24 isshown at D. An inspection of the curves reveals the fact that the curveI) may be approximately produced by superimposing the curve C upon thecurve B. This is substantially what occurs wl'ien the induced voltage ofthe transformer 22 is impressed across the receiving circuit. It isobvious, from a comparison of curvesB and D, that the peaks in the waveof rectified current are materially reduced and that the occurrence ofzero volts e is eliminated by the use of my corrective evice. The degreeof corrective efiect obtained is substantially represented by the ratiobetween the dimensions a." and 3/ which graphically repre sent thepercentages of periodic variation in the rectified waves with andwithout my corrective device. respectively.

\Vhile I have shown my rectifier in a simple and preferred form, it isnot so limited and it is also apparent that my corrective device may bcequally as Well applied to other types of rectifying apparatus such. forexample, as vapor converters that pro ducc a pulsating current in whichis desired to reduce the pcrccnta e of periodic varia tion. I desire.there ore. that only such limitations shall be placcd thereupon as arcimposed by the. prior art or are specifically set forth in the appendedclaims.

I I claim as my invention:

1. In a mechanical rectifying system. a rectifying commutator, a drivingmotor therefor. comprising rotor and stator windlugs. andmcansrrihnccling said commutator to said windings whereby the motorstarts as a single-phase sh'unt comnmtator motor and whereby. duringrectifying operation, said rotor Winding is so plied .with unidirectional current and said motor operates as a synchronous motor.

2. lo a mechanical rectifying system, a

rectifying commutator, a driving motor therefor, compri ing rotor andstator Windlugs, means connecting said commutator to said windingswhereby the motor starts as lllll single-phase induction motor, and forfinally driving motor embodying stator and rotor members respectivelyprovided with windings, a rectifying commutator mounted to be driven bysaid motor, connections whereby said stator winding is ener ized withalternating current and furt er connections whereby said rotor windingis supplied with direct current of the full voltage of said sourceduring synchronous o eration.

5. In a rectifying system, t e combination with a source of alternatingcurrent, of a driving motqr comprising rotor and stator membersrespectively provided with Windings, a rectifying commutator arranged tobe driven by said motor and embodying a moving element carrying nconducting segments and two fixed brushes arranged to bear upon saidsegments at points 360 apart,

and n being even, connections from said source to said brushes, meansfor connecting alternate segments into one group,means for connectingthe remaining segments into anie other group, means permanentlyconnecting said rotor winding between said two segment-groups, and meansconnecting one of said segment-groups to an intermediate point in saidsource through a load.

6. In a rectifying system, the combination-with a source of alternatingcurrent, of a driving motor comprising rotor and stator membersrespectively provided with windings, a rectifying commutator arranged tobe riven y said motor and embodying a moving element carrying itconducting segments and two fixed brushes arranged to bear upon saidsegments at points 360 apart, m

and n being positive integers, m being odd and n bein even, connectionsfrom said source to sai alternate segments into one group, means forconnecting the remaining segments into another group, means permanentlyconnectmg one of said windings between said two segment groups, meansconnecting one of said segment groups to an intermediate point in saidsource through a load, and means for connecting the remaining-windinacross said source of alternating current.

wi h

a source of alternating current, ,of a

driving motor com rising rotor and stator members res ective y providedwith windings, a rccti ying commutator arranged to be driven by saidmotor and embodying a moving element carryin n conducting seg- -'mentsand two fixed brus es arranged to bear m and n being positive integers,m being odd t, upon Smd Segments at pomts it 3600 apart or and n beingpositive integers, m being odd and n being even, connections from saidsource to said brushes, means for connecting alternate segments into onegroup, means for connecting the remaining segments into an- OLIVER S.JENNINGS.

brushes, means for connecting In a rectifying system, the combination

